From: Christoph Hellwig <hch@lst.de>
To: "Thomas Weißschuh" <linux@weissschuh.net>
Cc: Christoph Hellwig <hch@lst.de>, Keith Busch <kbusch@kernel.org>,
Jens Axboe <axboe@fb.com>, Sagi Grimberg <sagi@grimberg.me>,
linux-kernel@vger.kernel.org, linux-nvme@lists.infradead.org
Subject: Re: [PATCH] nvme-pci: fix host memory buffer allocation size
Date: Thu, 28 Apr 2022 17:06:44 +0200 [thread overview]
Message-ID: <20220428150644.GA22685@lst.de> (raw)
In-Reply-To: <5060d75e-46c0-4d29-a334-62c7e9714fa7@t-8ch.de>
On Thu, Apr 28, 2022 at 04:44:47PM +0200, Thomas Weißschuh wrote:
> Is the current code supposed to reach HMPRE? It does not for me.
>
> The code tries to allocate memory for HMPRE in chunks.
> The best allocation would be to allocate one chunk for all of HMPRE.
> If this fails we half the chunk size on each iteration and try again.
>
> On my hardware we start with a chunk_size of 4MiB and just allocate
> 8 (hmmaxd) * 4 = 32 MiB which is worse than 1 * 200MiB.
And that is because the hardware only has a limited set of descriptors.
Is there any real problem you are fixing with this? Do you actually
see a performance difference on a relevant workload?
next prev parent reply other threads:[~2022-04-28 15:07 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-04-28 10:19 [PATCH] nvme-pci: fix host memory buffer allocation size Thomas Weißschuh
2022-04-28 14:36 ` Christoph Hellwig
2022-04-28 14:44 ` Thomas Weißschuh
2022-04-28 15:06 ` Christoph Hellwig [this message]
2022-04-28 16:09 ` Thomas Weißschuh
2022-05-10 7:03 ` Christoph Hellwig
2022-05-10 10:20 ` Thomas Weißschuh
2022-05-25 15:07 ` Thomas Weißschuh
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